This present invention relates to the field of plastic bags including reclosable fastener strips with complementary male and female interlocking profiles.
The introduction of a plastic membrane film between the complementary profiles of a reclosable fastener strip to form a gasket and make the fastener strip watertight is already known.
For example, in DK 90 167, the closure strip is U-shaped in cross-section to the profiles in their longitudinal direction. There are two profiles. Each profile is located on one branch of the U. One of these branches is welded to one wall of a bag so that when the branches of the U are pressed against one another, the profiles close over both walls.
U.S. Pat. No. 3,164,186 describes a bag with a funnel that includes a reclosable fastener strip. A tubular film is welded to this strip so as to cover the inside wall of the part of the funnel that is attached to the strip. When the profiles are engaged, the film forms a watertight seal between the interlocking profiles.
U.S. Pat. No. Re 34,554 also describes reclosable fastener strips with one or two membranes. These membranes are welded to the strips or co-extruded with them, and form a watertight seal between the interlocking profiles when the latter are engaged.
These references thus disclose special reclosable fastener strips but do not disclose how to make watertight conventional reclosable fastener strips whose interlocking male and female profiles are already engaged.